1. Field of the Invention
The present invention relates to a radiation cassette having a housing for storing a radiation image recording medium and a lid openably and closably mounted on a portion of the housing.
2. Description of the Related Art
There is known a system for recording radiation image information of a subject such as a human body with a stimulable phosphor, and reproducing the recorded radiation image information on a photosensitive medium such as a photographic film, or displaying the recorded radiation image information on a display unit such as a CRT or the like.
The stimulable phosphor is a phosphor which, when exposed to an applied radiation (X-rays, xcex1-rays, xcex3-rays, electron beams, ultraviolet radiation, or the like), stores a part of the energy of the radiation, and, when subsequently exposed to applied stimulating rays such as visible light, emits light in proportion to the stored energy of the radiation. Usually, a sheet provided with a layer of the stimulable phosphor is used as a stimulable phosphor sheet.
It has been practiced to apply a radiation, e.g., X-rays, to a subject such as a human body, to record radiation image information of the subject directly on a photographic film. The radiation image information recorded on the photographic film is subsequently developed into a visible image, which will be used for a medical diagnosis or the like.
Each radiation image recording medium such as a stimulable phosphor sheet or a photographic film is usually housed in a cassette and loaded into an exposure apparatus where X-rays are applied to the radiation image recording medium through the cassette.
One known cassette is disclosed in Japanese patent publication No. 6-90424, for example. As shown in FIG. 9 of the accompanying drawings, the disclosed cassette comprises a housing 2 for housing a radiation image recording medium 1 therein, a lid 3 openably and closably mounted on a portion of the housing 2, and a light-shielding plate 4 disposed in a remaining portion of the housing 2 for holding the radiation image recording medium 1 in a light-shielded fashion in the housing 2 in coaction with the lid 3.
With the disclosed cassette, the radiation image recording medium 1 is loaded into and unloaded out of the housing 2 while the lid 3 mounted on the housing 2 is being open. The cassette has a gap between an inner surface of the housing 2 and the light-shielding plate 4. The gap is larger than the width of the radiation image recording medium 1 in order to allow the radiation image recording medium 1 to be smoothly and reliably taken into and out of the housing 2 and prevent the radiation image recording medium 1 from being scratched.
After the radiation image recording medium 1 is stored in the cassette, however, the radiation image recording medium 1 tends to move in the housing 2 because of the large gap between the inner surface of the housing 2 and the light-shielding plate 4. Consequently, the radiation image recording medium 1 cannot be held reliably in intimate contact with a lead plate, and it is difficult to perform a desired image forming process on the radiation image recording medium 1.
Particularly, if a copper plate is disposed on a side of the radiation image recording medium 1 where the radiation is applied, then the close contact that is achieved between the copper plate, the radiation image recording medium 1, and the copper plate serves as an important image forming condition to be fulfilled. With the disclosed cassette, however, such an important image forming condition cannot be satisfied because the lid 3 is openably and closably mounted on the portion of the housing 2.
It is a major object of the present invention to provide a radiation cassette of simple structure which is capable of holding a radiation image recording medium in intimate contact with a lead plate within a housing, with a lid openably and closably mounted on a portion thereof, and of smoothly loading the radiation image recording medium into the housing and unloading the radiation image recording medium out of the housing.
With a radiation cassette according to the present invention, a radiation image recording medium is loaded into and unloaded out of a housing when a lid mounted on a portion of the housing is open. After the radiation image recording medium is accommodated in the housing, when a radiation is applied to the radiation image recording medium, the radiation image recording medium is pressed against and supported on an inner surface of the housing by a support mechanism.
The radiation image recording medium can reliably be held in contact with a lead plate within the housing, allowing a desired image to be formed highly accurately on the radiation image recording medium. When the radiation image recording medium is loaded into and unloaded out of the housing, the radiation image recording medium is released from being pressed by the support mechanism. Therefore, the radiation image recording medium is smoothly and reliably delivered, and is effectively prevented from being scratched.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.